ACTIVITIES OF THYROID-HORMONES IN MEAT-TY PE AND EGG-TYPE JAPANESE-QUAILS

Egg production, growth, blood serum thyroxin (T4) and triiodo-thyronin e (T3) concentrations and T4 5'-monodeiodinase activity in liver homog enates were studied in lighter white egg-type (L and heavier wild meat -type (M) female Japanese quails (Coturnix coturnix japonica). Accordi ng to the results obtained, the body mass-gain was significantly highe r in the meat-type quails (Fig. 1) while the egg production was higher in the group of egg-type quails (Fig. 2). Blood samples were collecte d from quails of both types. Egg-type quails had lower serum T4 and T3 concentrations than meat-type quails (P < 0.05, ANOVA) (Figs 3, 4 and 6). The liver T4 5'-monodeiodinase activity was higher in meat-type q uails than in egg-type quails (Fig. 5). The findings have suggested th at lower T4 and T3, as well as 5'-monodeiodinase activities in egg-typ e quails means a certain metabolic adaptation to the egg production. H igh serum T3 concentration contributes the protein incorporation in me at-type quails.